A deep precipitation linkage regulation system for in-situ soil groundwater remediation

Abstract

The utility model discloses a kind of deep precipitation linkage control systems for in situ soil groundwater remediation.The system includes slurry pump (1), liquid discharge pump (2), negative pressure fan (3), three-phase separation tank (4), control module (5) and multiple precipitation wells (7) laid in precipitation site (6).Each precipitation well (7) is equipped with a set of precipitation device (7-1) including air jet pipe (7-2) and extraction pipe (7-3).The core of the utility model is, by negative pressure fan (3) provides extraction power, forms gas-water mixture and is transported to three-phase separation tank (4) and carries out gas, liquid, solid three-phase separation;Meanwhile, according to the flow signal detected by each well flowmeter FI (7-4), the opening of corresponding gas flow control valve FCV (7-5) is adjusted in real time, to accurately control the extraction water volume of each well.The utility model breaks through the application limit of traditional pump under the condition of deep layer, small well diameter, realizes the accurate precipitation of multi-well cooperation, high efficiency and energy saving.

Description

Technical Field

[0001] This utility model relates to the field of soil and groundwater remediation technology, and in particular to a deep precipitation linkage control system for in-situ soil and groundwater remediation. Background Technology

[0002] In the field of soil and groundwater pollution remediation, especially in the implementation of in-situ remediation technologies (such as in-situ leaching, in-situ chemical oxidation / reduction, in-situ bioremediation, and groundwater circulation well technology), the efficient and reliable continuous extraction of large volumes of water from deep groundwater wells is a common and crucial technological foundation. These precipitation operations are mainly used to create hydraulic control barriers, drive the diffusion of remediation agents, remove dissolved pollutants, or regulate groundwater flow fields.

[0003] The groundwater wells targeted by this type of pumping operation typically exhibit the following significant characteristics: significant depth, with the target aquifer often reaching depths of tens or even hundreds of meters; limited well diameter, with extremely narrow inner diameter spaces in the well casing (casing), mostly on the order of centimeters (e.g., DN50 to DN150); high flow rate requirements, with single wells or well groups needing to meet large design extraction flow rates to achieve effective contaminant control or remediation media transport; and complex water quality, with the extracted groundwater often containing high concentrations of dissolved contaminants, fine particulate matter (SS), and potentially corrosive or scaling chemical components, resulting in a harsh operating environment. Currently, conventional groundwater extraction equipment and technologies face severe challenges in meeting the comprehensive operating conditions of "deep depth, small well diameter, large flow rate, and complex water quality": Conventional submersible pumps / deep well pumps often have a physical outer diameter that is difficult to adapt to the narrow casing of deep wells; in extremely deep wells, head reduction and efficiency decrease are prominent issues, and high-head pumps usually sacrifice flow rate; the reliability, wear resistance, and lifespan of long-term operation in high-solids or corrosive media are difficult to guarantee. While submersible pumps (long-shaft pumps) can adapt to certain depths through their slender shafts, their pump body diameter is still strictly limited by the well diameter, thus limiting their flow capacity; long drive shafts in deep wells are prone to vibration, wear, and alignment difficulties, resulting in frequent and costly maintenance; they are also sensitive to suspended particles in the water, easily clogging or wearing out. Small submersible pumps, although adaptable to small well diameters, typically have low single-unit head and flow capacity, making it difficult to meet the high flow rate requirements of deep wells; multi-pump parallel solutions in deep wells are complex to deploy, have low energy efficiency, and increase reliability risks. Therefore, existing dewatering equipment and technologies are significantly insufficient for deep, small-diameter groundwater wells, while simultaneously meeting high flow rate requirements and ensuring long-term stable operation under complex water quality conditions. This technological bottleneck directly restricts the engineering application effectiveness, implementation efficiency, economic viability, and large-scale promotion potential of various in-situ soil and groundwater remediation technologies that rely on efficient deep dewatering. Utility Model Content

[0004] The purpose of this invention is to overcome the aforementioned shortcomings of existing deep groundwater dewatering technologies and provide a compact, depth-attenuation-free, easy-to-deploy and-maintain deep groundwater co-dewatering system that enables preliminary stripping of pollutants during the extraction process. Specific objectives include: overcoming the limitations of traditional pump size and head to achieve stable high-flow-rate groundwater extraction under conditions of great depth (tens to hundreds of meters) and small well diameter (centimeter-level); solving the problems of large fluctuations in single-well extraction volume, uneven hydraulic control in the remediation area, and uneven remediation effects caused by differences in distance between multiple wells and uneven gas distribution; significantly reducing overall system energy consumption and improving energy utilization efficiency; simplifying the system structure and reducing construction complexity and maintenance costs; and simultaneously achieving preliminary stripping of volatile / semi-volatile organic pollutants during the extraction process.

[0005] The technical solution of this utility model is a deep precipitation linkage control system for in-situ soil groundwater remediation, the system composition of which is as follows:

[0006] a. Well Cluster and Core Equipment: The system includes multiple dewatering wells (7) located at the dewatering site (6), as well as a mud pump (1), a drainage pump (2), a negative pressure fan (3), a three-phase separator (4), and a control module (5) located on the ground. Each dewatering well (7) is equipped with a dewatering device (7-1), which includes a jet pipe (7-2) extending into the well and a extraction pipe (7-3).

[0007] b. Fluid pipeline connection: The outlets of the extraction pipes (7-3) of all the dewatering wells (7) are connected to the inlet of the three-phase separator (4); the mud outlet of the three-phase separator (4) is connected to the mud pump (1), the liquid outlet is connected to the drain pump (2), and the gas outlet is connected to the inlet of the negative pressure fan (3); one of the outlet pipelines of the negative pressure fan (3) is connected to the jet pipe (7-2) of each dewatering well (7) as a circulating gas path, and the other is connected to the external exhaust gas treatment device.

[0008] c. Monitoring and control system: The system also includes a flow meter FI (7-4) installed on the extraction pipe (7-3) of each dewatering well (7) and a gas flow control valve FCV (7-5) installed on the jet pipe (7-2) of each dewatering well (7); the flow meter FI (7-4) and the gas flow control valve FCV (7-5) are both electrically connected to the control module (5), thereby forming a closed-loop control system that adjusts the intake air volume according to the actual flow feedback.

[0009] d. Preferably, the precipitation device (7-1) may adopt a structure including a gas collection hood as authorized by patent number ZL201811183213.7, wherein the outlet of the jet pipe (7-2) is located inside the gas collection hood, and the inlet of the extraction pipe (7-3) is connected to the gas collection hood.

[0010] The workflow of this utility model system is as follows:

[0011] 1. System startup and gas path establishment: Start the negative pressure fan (3), which establishes extraction negative pressure in the system. This negative pressure is transmitted to the bottom of each precipitation well (7) through the extraction pipe (7-3), and at the same time acts on the entire system through the three-phase separator (4).

[0012] 2. Gas Lifting and Water Mixing: A portion of the gas from the outlet of the negative pressure fan (3) is transported as circulating gas to the jet pipes (7-2) of each dewatering well (7) and ejected at high speed in the dewatering device (7-1). The ejected gas mixes with groundwater at the bottom of the well to form a low-density gas-water mixture.

[0013] 3. Mixture extraction and transportation: Under the negative pressure of the system, the above gas-water mixture is drawn into the extraction pipe (7-3) and transported to the three-phase separator (4) on the ground through the collection pipeline.

[0014] 4. Three-phase separation process: The gas-liquid-solid mixture entering the three-phase separator (4) undergoes the following separation stages in sequence:

[0015] Solid phase separation: Using the principle of gravity sedimentation, most of the mud in the mixture is separated and discharged from the system by mud pump (1).

[0016] Liquid phase separation: The gas-liquid two-phase mixture after solid phase separation is deeply separated through mechanisms such as gravity sedimentation and coalescence, and the clarified liquid is discharged from the system through the drain pump (2).

[0017] Gas phase purification: The separated gas passes through a wire mesh demister or high-efficiency filter to remove entrained trace droplets and solid particles, resulting in a relatively clean gas.

[0018] 5. Gas Circulation and Exhaust Gas Treatment: After purification, the gas is drawn in and pressurized by the negative pressure fan (3), and its outlet airflow is divided into two paths: the main path is used as a circulating gas path to return to the jet pipes (7-2) of each well for reuse; the branch path is used as exhaust gas to be discharged into the external treatment device. In order to maintain the gas volume balance of the system, an air replenishment port is provided at the outlet of the negative pressure fan (3).

[0019] 6. Intelligent flow closed-loop control:

[0020] Monitoring: The flow meter FI (7-4) installed on the extraction pipe (7-3) of each precipitation well (7) detects the flow rate of the gas-water mixture in real time and transmits the signal to the control module (5).

[0021] Comparison and decision: The control module (5) compares the received actual flow signal with the preset target flow value and calculates the adjustment command through the built-in algorithm.

[0022] Execution and Adjustment: The control module (5) sends the adjustment command to the gas flow control valve FCV (7-5) on the jet pipe (7-2) of the corresponding dewatering well (7), and controls the amount of air entering the well by precisely adjusting its opening, thereby achieving precise control of the amount of water extracted.

[0023] Collaborative control: The control module (5) balances the extraction volume of each well by executing a multi-well collaborative control strategy, ensuring the uniformity and stability of the hydraulic gradient of the entire precipitation site (6).

[0024] Beneficial Effects: The in-situ soil and groundwater remediation technology for deep groundwater precipitation regulation and control of this invention addresses the problem of mismatch between extraction volume and gas usage in multi-diameter extraction processes. By combining pneumatic transport principles, it overcomes the limitations of extraction depth and enables timely treatment of groundwater contamination. Compared with existing deep groundwater precipitation control technologies, the in-situ soil and groundwater remediation technology for deep groundwater precipitation regulation and control provided by this invention has the following significant advantages:

[0025] Breaking through physical limitations to achieve deep and efficient groundwater extraction: The core technology utilizes pneumatic conveying principles, completely eliminating the need for traditional mechanical pump structures. This design fundamentally eliminates the depth bottleneck caused by pump size and head limitations, enabling the system to stably and efficiently extract large volumes of groundwater under harsh conditions, including depths of hundreds of meters and narrow well diameters of centimeters. This solves a fundamental problem that existing technologies struggle to overcome.

[0026] Multi-well collaborative control for precise and stable flow: This invention revolutionarily solves the problem of uneven gas intake distribution caused by differences in pipeline distance and resistance in multi-well operations through an intelligent gas volume control system based on real-time feedback. The system can monitor the actual water output of each well in real time and dynamically and precisely adjust the gas flow rate (volume) input to each well, ensuring that the extraction volume of a single well strictly meets the preset target, achieving multi-well collaboration and balanced and stable flow. This effectively guarantees the uniformity and controllability of the hydraulic gradient in the pollution remediation area, significantly improving the consistency and reliability of the remediation effect.

[0027] Optimizing gas-liquid matching significantly improves energy efficiency: Traditional extraction or decentralized control often suffers from mismatches and inconsistencies between gas supply and flow demand, leading to severe energy waste. The intelligent control mechanism of this invention, through dynamic optimization of the gas-liquid ratio (the relationship between gas and water volume) of each well and the use of a separate gas path provided by a negative pressure fan, maximizes the utilization of extracted gas. The system adaptively provides the minimum effective gas volume required to meet the target flow rate, significantly reducing overall system energy consumption and operating costs, and resulting in a substantial improvement in energy utilization efficiency.

[0028] The structure is highly simplified, and deployment and maintenance are convenient: the downhole unit only requires the installation of jet pipes and extraction pipes, without complex mechanical transmission components or underwater motors, resulting in an exceptionally simple and compact structure. This greatly simplifies installation, disassembly, and maintenance operations in narrow, deep wells, significantly reducing construction complexity, time costs, and potential risks. The surface equipment adopts a modular design, facilitating transportation, installation, and expansion, and demonstrating strong engineering adaptability.

[0029] Simultaneous pollutant stripping and integrated preliminary treatment: While extracting groundwater using pneumatic conveying principles, the injected compressed air and contaminated water undergo vigorous mixing within the riser pipe. This process itself constitutes a highly efficient in-situ air stripping unit. This mechanism effectively promotes the transfer of volatile and semi-volatile organic pollutants (VOCs / SVOCs) from groundwater to the gas phase. Combined with a matching surface-mounted air stripping exhaust gas treatment device, this invention innovatively achieves integrated "extraction-stripping," completing the preliminary separation and treatment of pollutants while extracting groundwater, reducing the load on subsequent treatment units, and improving the overall efficiency of the remediation process.

[0030] Exceptional environmental adaptability and operational reliability: The system has no underwater precision or rotating parts, exhibiting strong tolerance to the high concentrations of suspended solids (SS), corrosive ions (such as chloride and sulfate ions), and complex chemical components commonly found in groundwater. This avoids common problems in traditional pump technology, such as wear, clogging, and corrosion failure, ensuring the system's reliability and durability for long-term, continuous, and stable operation under harsh water quality conditions.

[0031] Intelligent operation ensures controllable results: The closed-loop feedback control system based on real-time data enables the system to adaptively adjust and optimize its operation. It not only precisely controls water volume but also continuously optimizes control parameters based on operational data (such as pressure and gas-liquid ratio), ensuring the continuous controllability of the restoration effect and providing data support for project management. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of the system of this utility model.

[0033] In the diagram: 1. Mud pump; 2. Drain pump; 3. Negative pressure fan; 4. Three-phase separator; 5. Control module; 6. Dewatering site; 7. Dewatering well; 7-1. Dewatering device; 7-2. Jet pipe; 7-3. Extraction pipe; 7-4. Flow meter (FI); 7-5. Gas flow control valve (FCV). Detailed Implementation

[0034] The specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings, in order to help those skilled in the art fully understand the actual operation and running process of this utility model, rather than to limit the scope of protection of this utility model.

[0035] In its implementation, the core of this system lies in combining pneumatic lifting with intelligent control to achieve precise and coordinated extraction of deep groundwater. The system's deployment on the ground should adhere to a modular principle to facilitate transportation, installation, and maintenance.

[0036] 1. System Composition and Deployment

[0037] The physical structure of the system mainly includes multiple dewatering wells 7 deployed at the dewatering site 6, and a core processing unit centrally located on the ground. The ground unit mainly includes a mud pump 1, a drainage pump 2, a negative pressure fan 3, a three-phase separator 4, and a control module 5.

[0038] Each dewatering well 7 is equipped with a dewatering device 71. This device is crucial for the system's deep extraction capability, and its core components include a jet pipe 72 extending deep into the groundwater level and an extraction pipe 73. In actual installation, the outlet end of the jet pipe 72 should be positioned below the inlet of the extraction pipe 73 to ensure that the gas can effectively lift the groundwater. The outlets of the extraction pipes 73 from all dewatering wells 7 are connected to the inlet at the top of the three-phase separator 4 via a pipeline network.

[0039] 2. Core Unit Connections and Functions

[0040] The three-phase separator 4 performs the core function of separating the gas, liquid, and solid phases. The mud outlet at the bottom of the tank is connected to the mud pump 1 via a pipeline for periodically or continuously discharging settled solid particles. The liquid outlet in the middle of the tank is connected to the drain pump 2, which transports the separated groundwater to the subsequent water treatment unit. The gas outlet at the top of the tank is connected to the inlet of the negative pressure fan 3.

[0041] The negative pressure fan 3 serves as the power source for the entire system. Its outlet pipe is divided into two paths via a tee: the main loop acts as a circulating air path, connecting to the jet pipes 72 of each dewatering well 7 through a pipeline network to provide continuous power for groundwater lifting; the branch loop connects to an external exhaust gas treatment device to discharge excess gas or gas enriched with pollutants from the system. To maintain pressure and air volume balance within the system, an air supply port with a filter is installed on the outlet pipe of the negative pressure fan 3 before the branching off from the main loop.

[0042] 3. Implementation of Monitoring and Control

[0043] The system's intelligence is reflected in its closed-loop feedback control circuit. Each well 7's extraction pipe 73 is equipped with a flow meter FI74 for detecting the instantaneous flow rate of the gas-water mixture; a corrosion-resistant mass flow meter is preferred. Each well 7's jet pipe 72 is equipped with a gas flow control valve FCV75, which allows for precise adjustment of its opening; a gas proportional control valve with a fast response time is preferred.

[0044] Control module 5, which can be an industrial PLC or DCS system, is electrically connected to all flow meters FI74 and gas flow control valves FCV75 via signal cables, thereby constructing a distributed closed-loop feedback network that can independently and precisely control each well.

[0045] 4. System Workflow

[0046] When the system starts up, the negative pressure fan 3 is turned on first. After the fan starts running, a stable negative pressure environment is formed in the entire extraction pipeline and the three-phase separator 4. At the same time, part of the gas from the fan outlet is transported to the jet pipe 72 of each well through the main circuit and sprayed into the water at the bottom of the well at high speed.

[0047] The ejected gas mixes violently with groundwater, forming a low-density gas-water mixture. Driven by the negative pressure of the system, this mixture is continuously drawn into the extraction pipe 73 and lifted and transported to the three-phase separation tank 4 on the ground.

[0048] The mixture entering the three-phase separator 4 first undergoes solid-liquid separation in the gravity settling zone, with the slurry settling to the bottom of the tank. Subsequently, the gas-liquid mixture rises to the coalescence separation zone, where deep separation of gas and liquid is achieved, and the liquid is captured. Finally, the gas enters the top demister filter section, where a built-in wire mesh demister removes entrained micro-droplets and particles, resulting in clean gas.

[0049] The separated liquid is discharged by drain pump 2, the slurry is discharged by slurry pump 1, and the clean gas is drawn in by negative pressure fan 3. After the fan pressurizes this gas, most of it re-enters the main circuit for recycling, and a small portion is discharged as exhaust gas, thus forming a highly efficient and energy-saving circular operation process.

[0050] 5. Implementation of intelligent control logic

[0051] The control module 5 has a preset target extraction flow rate for each dewatering well 7. During operation, the flow meter FI74 of each well continuously transmits the detected actual flow rate signal to the control module 5.

[0052] Control module 5 compares the actual flow rate with the target flow rate. If a deviation exists, it performs calculations using built-in PID and other control algorithms and immediately sends an adjustment command to the gas flow control valve FCV75 of the corresponding well. By increasing or decreasing the valve opening, the amount of gas entering the well can be adjusted, thereby precisely controlling the water extraction rate and stabilizing it near the target value.

[0053] Crucially, control module 5 is configured to execute a multi-well collaborative control strategy. It can comprehensively analyze the flow data of each well and dynamically adjust the opening degree of each FCV75 to balance the extraction volume among the well groups, ensuring a uniform and controllable groundwater flow field in the remediation area, thereby guaranteeing the consistency and reliability of the overall remediation effect.

[0054] The above description is merely a typical embodiment of this utility model. Those skilled in the art can make various improvements and modifications based on the concept of this utility model, and all such equivalent modifications and variations should fall within the protection scope defined by the claims of this utility model.

[0055] 6. Example

[0056] To illustrate the technical effects of this invention, a typical application embodiment is provided. This system was applied in a groundwater pollution remediation project in Nanjing to treat groundwater with high solids content, where the sand content is no higher than 5% and the suspended solids concentration is no higher than 200 mg / L.

[0057] In this embodiment, the specific implementation parameters and performance of the system are as follows:

[0058] System configuration: Well casing diameter range for extraction wells: φ50 mm~φ100 mm, effective extraction depth: 40~70m.

[0059] Energy efficiency: The system's single-well extraction energy consumption is 0.8–1.2 kW·h / m³, saving more than 60% energy compared to traditional submersible pumps (≥3.0 kW·h / m³). Processing efficiency: Average daily extraction capacity per well is 10–30 m³.

[0060] Flow stability: The measured fluctuation after 72 hours of continuous operation is ≤±7%.

[0061] System reliability: Fault-free operating time: ≥2000 h.

[0062] Adaptability to sandy conditions: Stable treatment of groundwater with a sand content of 5%.

[0063] Comparison of technical advantages:

[0064] The unit energy consumption of this technology is 0.8–1.2 kW·h / m³, with sand content adaptability ≤5% and flow fluctuation ≤±7%; the unit energy consumption of traditional technology is ≥3.0 kW·h / m³, with sand content ≤2% and flow fluctuation ≥±15%. Improvement effect: Unit energy consumption is reduced by more than 60%, anti-interference ability is improved by more than 150%, and stability is improved by more than 2 times.

[0065] This embodiment fully demonstrates that the present invention successfully overcomes the application bottlenecks of traditional technologies in deep, small-diameter, and complex water quality conditions, and comprehensively achieves the goals of efficient, energy-saving, stable, and reliable precipitation operations.

Claims

1. A deep precipitation linkage control system for in-situ soil groundwater remediation, characterized in that, include: Mud pump (1), drain pump (2), negative pressure fan (3), three-phase separator (4), control module (5), and one or more dewatering wells (7) installed at the dewatering site (6); Each of the dewatering wells (7) is equipped with a dewatering device (7-1), which includes a jet pipe (7-2) extending into the well and a extraction pipe (7-3); The outlets of the extraction pipes (7-3) of all the aforementioned precipitation wells (7) are combined and connected to the inlet of the three-phase separator (4); the mud outlet of the three-phase separator (4) is connected to the inlet of the mud pump (1), its liquid phase outlet is connected to the inlet of the discharge pump (2), and its gas phase outlet is connected to the inlet of the negative pressure fan (3). The outlet pipe of the negative pressure fan (3) is divided into two paths: one path is connected to the jet pipe (7-2) of all the precipitation wells (7) as a circulating air path, and the other path is connected to the external exhaust gas treatment device. The system also includes a flow meter FI (7-4) installed on the extraction pipe (7-3) of each dewatering well (7), and a gas flow control valve FCV (7-5) installed on the jet pipe (7-2) of each dewatering well (7); the flow meter FI (7-4) and the gas flow control valve FCV (7-5) are both electrically connected to the control module (5).

2. The system according to claim 1, characterized in that, The precipitation device (7-1) includes a gas collection hood, the outlet of the jet pipe (7-2) is located inside the gas collection hood, and the inlet of the extraction pipe (7-3) is connected to the gas collection hood.

3. The system according to claim 1, characterized in that, The three-phase separator (4) is provided with, from bottom to top, a solid phase separation section that utilizes the principle of gravity sedimentation, a liquid phase separation section that achieves deep gas-liquid separation, and a gas phase refining section equipped with a wire mesh demister or a high-efficiency filter.

4. The system according to claim 1, characterized in that, An air supply port for replenishing the system air volume is provided on the outlet pipe of the negative pressure fan (3) before the circulating air path branches out.

5. The system according to claim 1, characterized in that, The gas flow control valve FCV(7-5) is a gas proportional control valve.

6. The system according to claim 1, characterized in that, The flow meter FI(7-4) is a mass flow meter.

7. The system according to claim 1, characterized in that, The control module (5) is configured to receive the actual flow signal detected by each of the flow meters FI (7-4), compare it with the preset target flow value, and output an adjustment command to the corresponding gas flow control valve FCV (7-5) to control the extraction water volume by adjusting the air intake.

8. The system according to claim 7, characterized in that, The control module (5) is configured to execute a multi-well collaborative control strategy to balance the extraction volume among the various dewatering wells (7).

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